Internship at the University of Gttingenin the field of particle
physics of the top quark
Contact information
Philipp StolteII. Physikalisches Institut
Georg-August-Universitt GttingenFriedrich-Hund-Platz 137077
Gttingen, Germany E-Mail: [email protected]
Research questions and your tasks
We would like to offer an internship in the field of elementary
particle physics, a field which addresses the questionabout the
elementary constituents of matter at the most fundamental level,
i.e. the smallest possible scale of size.Today's experiments in
this field are based on collisions of particles obtaining their
high energy from accelerators.With a decreasing scale of the
participating particles, higher and higher energies and thus larger
colliders areneeded. Nowadays, the Large Hadron Collider at CERN in
Geneva is the most powerful particle accelerator inthe world,
designed to reach beam energies of up to 7 TeV in proton-proton
collisions. Recent measurements ledto the discovery of the Higgs
boson after long and intensive searches, as discussed thoroughly in
the internationalmedia. In 2013, Peter Higgs and Francois Englert
received the Nobel Prize in Physics for the theoretical
predictionof this boson.Apart from the Higgs boson, many other
particles are produced at the LHC in large quantities. One of
theseparticles is the top quark, the heaviest elementary particle
of the Standard Model. Top quarks play an essentialrole in the
field of particle physics especially due to their remarkable
properties comprising a large mass, whichis approximately
comparable to the mass of a tungsten atom, and an extremely short
lifetime: Examining thisquark in more detail and measuring its
properties serves, for instance, to test the established Standard
Model ofparticle physics and the results may also hint at unknown
physics beyond this model.
One of the quantities of the top quark which has not yet been
measured directly at themultipurpose detectors ATLAS and CMS at the
LHC is the decay width of the topquark. The ATLAS top quark group
in Gttingen works on the realisation of thismeasurement for which
we use ATLAS data recorded at a centre-of-mass energy of 7and 8 TeV
in proton-proton collisions at the LHC in 2011 and 2012,
respectively. Theadvantage of a direct measurement is its
model-independence which also includes that abroader class of
models involving physics beyond the Standard Model can be probed.
Such a direct measurement has been performed by the CDF
Collaboration at theTevatron accelerator, but suffered from large
uncertainties. The large statistics availableat the LHC will help
to reduce the statistical uncertainty with respect to the CDF
result,but we also need to analyse the systematic uncertainty in
detail. Next summer, we will bein the process of finalising the
work on this measurement. During your stay in Gttingenyou are able
to participate in these last and important studies to finish the
analysis, e.g.last studies concerning the impact of systematic
uncertainties. A further task you areinvolved in would be a first
examination of new ATLAS data taken at a centre-of-mass energy of
13 TeV withwhich this top decay width measurement is planned to be
repeated. You will work with code using commands ofthe data
analysis framework ROOT, based on C++-code. With your project, you
directly take part in important andnecessary studies for this new
and demanding measurement.
The University of Gttingen and our institute
During your internship you will work in the Institute for
Nuclear andParticle Physics of our university placed in the north
of Gttingen. Ourgroup is very international with researchers coming
from all over theworld. The faculty building is very new and
modern, providing anexcellent environment to work and study.
Gttingen, located close to thegeographical centre of Germany, has
around 120,000 inhabitants, almostone fifth of them are students.
This leads to a very special atmosphere ofthe city hardly any other
city in Germany is shaped by the university insuch a way. Many pubs
and bars in the famous historic city centre allowyou to enjoy the
evenings after work. Furthermore, there are a lot of sportgrounds,
parks and sights for various weekend activities.
